Not sure what your car needs?

Manage your car online

Q:
Brand new battery keeps being drained. I found the interior light switch does not work. Could this be the culprit?

asked by
Cynthia G
on
October 22, 2016

Bought the car used. Has brand new battery. Keeps being drained and car won't start if not driven for greater than 16 hrs. No problem was disclosed. Already checked all the fuses and removed the fuse for the cigeratte lighter that looked bad. So frustrating as I really can't afford a fishing expedition at a dealership.

My car has 137000 miles.
My car has an automatic transmission.

Services recommended for this issue

Enter your car for a more accurate estimate

Even though you have a "new" battery, it does have to be load tested just to be sure. Such is not a problem though as many large battery vendors will do it for free. Once you have confirmed the battery, you want to check the output of the alternator and compare against the Factory Service Manual (typically output should be around 13.8 to 14.5 volts but the FSM spec is the one to rely on). If all that checks out, you have a phantom load on one of the car’s circuits that is drawing a significant amount of current when the car is off. Normally, some battery power is required to keep the car "alive" when it is sitting in your garage (alarm, computer, clock, etc.) but this current draw is so small, at around 50 milliamps, that it won’t discharge the battery "quickly". Basically, to find the phantom load(s), when the car is off, you measure the amp draw from the battery to each and every circuit fed by the battery. If you do this methodically, eventually the circuit that is discharging the battery will show up. That individual circuit(s) is then traced to identify the faulty device and or wiring issue that is letting current flow when it should not flow.

Get an instant quote for your car

What others are asking

Q: Ac compressor clutch isn't engaging on high fan speed setting while it engages on the prior three fan speeds which are all slow.

The blower not working is most likely due to a fault with the blower resistor. When you go to high blower speeds the A/C may disengage the compressor if the cycling switch cycles or the high pressure switch gets over...

Q: Can a loose battery terminals cause the radio to shut off while car is running in a mecedes e350

Hi there. Typically when the vehicle is running, power to accessories and ancillary components like the AC system will be supplied by the alternator. This means that when you have inconsistent power problems like you've described, it is usually due...

Q: A/c wont turn off mitsubishi lancer gts 08

The circuit has to be restored to its original configuration particularly as you mention that a relay might have been removed. If you request an electrical circuit/component diagnostic the responding certified mechanic will compare the wiring diagram in the Factory...